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InterviewSolution
| 1. |
What is self inductance of a coil ? Write its SI unit . Obtain the expression for energy store a in an inductor. |
| Answer» <html><body><p></p>Solution :<a href="https://interviewquestions.tuteehub.com/tag/self-1199734" style="font-weight:bold;" target="_blank" title="Click to know more about SELF">SELF</a> inductance of a coil is numerically equal to the emf induced in the coil due to unit rate of change of current in it. The SI unit of self inductance in henry (H). <br/> <a href="https://interviewquestions.tuteehub.com/tag/let-11597" style="font-weight:bold;" target="_blank" title="Click to know more about LET">LET</a> dw be the work <a href="https://interviewquestions.tuteehub.com/tag/done-2591742" style="font-weight:bold;" target="_blank" title="Click to know more about DONE">DONE</a> to establish a current I in the coil in a time dt. <br/> Then `(dw)/(dt)=|<a href="https://interviewquestions.tuteehub.com/tag/epsilon-973455" style="font-weight:bold;" target="_blank" title="Click to know more about EPSILON">EPSILON</a>|I "" epsilon` is the induced emf <br/> since `epsilon=-L (dI)/(dt)` <br/> `(dw)/(dt)=L(dI)/(dt)I` <br/> `dw=L(dI)/(canceldt)canceldtI` <br/> dw=LI dI <br/> The <a href="https://interviewquestions.tuteehub.com/tag/total-711110" style="font-weight:bold;" target="_blank" title="Click to know more about TOTAL">TOTAL</a> work done in establishing the current is , <br/> `W=int dw=int_0^I L I dI =L[I^2/2]_0^1` <br/> `W=1/2LI^2` <br/> Thus the magnetic P.E. stored in an inductor of self inductance L carrying a current I is <br/> `W=1/2LI^2`</body></html> | |